Module destruction is missing

[isac322]

Feature

https://github.com/python/cpython/blob/5442561c1a094b68900198bade616da9ed509ac8/Lib/test/test_sys.py#L963-L982 test_sys::SysModuleTest.test_is_finalizing

In TC, AtExit.__del__ is not invoked. Because ref = AtExit() is a module attribute, RustPython must implement module destruction to invoke it.

Found during work on #3776